1995] TRANSEAU—BOGS OF THE HURON RIVER VALLEY 355 
to the Kankakee River, and reached the Mississippi by way of the 
Illinois. 
As the reentrant extended itself further to the northeast, another 
channel was opened for the Huron drainage westward past Pinckney 
into the Grand River, and from there to Battle Creek and the Kala- 
mazoo River. Below the city of Kalamazoo it cut across to the Paw 
Paw River, and reached the Mississippi by way of Lake Chicago. . 
When the ice of the Erie lobe had retreated as far eastward as 
Ann Arbor, and all of the interlobate moraine had been uncovered, 
a third outlet for the waters of the Huron was opened by way of 
Clinton and the Raisin River, which at that time emptied into glacial 
Lake Maumee at Adrian ( 32, pl. 20). This lake was drained by 
the Wabash River into the Mississippi. 
As soon as the ice margin passed the clay morainic belt already 
described, the Huron reached Lake Maumee at Ypsilanti by way of 
its Present channel. But Lake Maumee had meanwhile changed 
ts outlet to the northward, its drainage going by way of Imlay (53) 
to the Grand River, Lake Chicago, and the Mississippi (32, ls. 
21, 23, 26), 
Later the Erie basin was entirely freed of ice, and its water for 
the first time flowed eastward into the Ontario basin (glacial Lake 
Iroquois), and thence by way of the Mohawk to the Hudson. With 
me clearing of the St. Lawrence channel the present system was 
inaugurated, 
_Aside from the physiographic interest connected with their early 
history, these glacial drainage channels are of distinct biological 
‘St. They furnish continuous lowland habitats extending in 
es In so far as they are represented by broad, a ine 
‘YS, and connect with tributaries of the northern Ohio valley, 
Provide important highways for the dispersal of southern river- 
€Y species. 
FORESTS. 
: The three topographic divisions already described exhibit marked 
tiga in their forest aspect. On the lake plain we find the 
iia and most mesophytic of the forest types. This | lowland 
_,» # Continuation of the northern Wabash valley, and it is not 
“uprising that its flora should be of much the same character. Here 
